The invention discloses a method for regenerating a positive active material from waste 
lithium iron phosphate batteries. The method comprises the steps as follows: 1) waste 
lithium iron phosphate batteries are discharged in 
saline water, and organic solvents, roll cores and casing materials are disassembled; 2) the roll cores are subjected to crushing, 
calcination and other steps, and active materials, 
copper foil and 
aluminum foil are separated through vibrating screening. 
Fluorine-containing 
waste gas is absorbed with 
lime water, the 
copper foil and the 
aluminum foil are separated with a 
magnetic separation method, the active materials are leached out with 
sulfuric acid, and a 
leachate and carbon residues are obtained through separation; 3) Cu<2+> in the 
leachate is reduced to elementary 
copper by adding 
iron powder, meanwhile, Fe<3+> is reduced to Fe<2+>, copper and excessive iron residues are filtered out, aluminum is removed through 
precipitation with an alkaline liquid, the filtrate is supplemented with a 
phosphorus source after 
filtration, the pH value is adjusted by adding the alkaline liquid, coarse 
lithium iron phosphate precipitates are produced, and finally, battery-grade 
lithium iron phosphate is obtained through 
sintering. Comprehensive utilization of the waste 
lithium iron phosphate batteries and regeneration of the active materials are realized with a simple, practical, economical and feasible method, no secondary 
pollution is produced, and the method is suitable for industrial production.